1. Technical Field
The present invention relates to a liquid ejecting head such as ink jet type recording head and, more specifically, to a liquid ejecting head in which liquid stored in a liquid storing member is introduced into pressure chambers via liquid flow channels, and the liquid introduced into the pressure chambers is discharged as ink drops from nozzle openings.
2. Related Art
Examples of liquid ejecting head for discharging liquid in pressure chambers as liquid drops from nozzle openings by causing pressure variation therein includes an ink jet type recording head (hereinafter, referred to simply as “recording head”) used in an image recording apparatus such as an ink jet type recording apparatus (hereinafter, referred to simply as “printer”), a color material ejecting head used for manufacturing color filters of liquid crystal display or the like, an electrode material ejecting head used for forming electrodes, for example, in an organic EL (Electro Luminescence) display and an FED (surface emission type display), and a biological organic substance ejecting head used for manufacturing biochips.
For example, in the above-described recording head, ink in an ink cartridge is introduced to the pressure chamber side of the recording head through introduction holes opened on the distal end sides of ink introduction needles by inserting the ink introducing needles, which are a kind of liquid introduction needle, into the ink cartridge as a liquid storage member including ink in liquid state sealed therein. There is proposed a configuration in which the ink cartridge arranged on a main body of the printer and the ink introducing needles of the recording head are connected with ink tubes, so that the ink in the ink cartridge is fed into the recording head with a pump or the like.
An ideal state in the recording head in the configuration described above is such that ink flow channels (liquid flow channels) extending from the ink introduction needles to the nozzle openings of the recording head are filled with ink. However, it is difficult to avoid entry of air bubbles into the ink flow channels completely when, for example, filling ink into the recording head (initial filling). The air bubbles entered into the ink flow channels are grown to large sizes with time, and hence when the excessively grown air bubbles pass through filters in the filter chambers arranged partway in the ink flow channels and move to the pressure chamber side by the ink flow, defects such as pressure loss due to the air bubbles absorbing the pressure variation during discharging operation, or ink supply shortage due to the air bubbles clogging the flow channels may be resulted.
In order to prevent such defects due to the air bubbles, there is proposed a method of increasing an air bubble expellant efficiency so as to prevent air bubbles from staying in the ink flow channel as much as possible. For example, a configuration in which air bubble introducing grooves are provided on the inner peripheral surfaces of the ink introducing needles in the vicinity of the filter (filter mounting member) so that the air bubbles in the ink flow channels are guided to the downstream side positively by these air bubble introducing grooves (See JP-A-11-078046).
However, In a configuration in the related art, when the air bubbles are grown to large sizes in the interior (filter chamber) of the ink introduction needle, even though cleaning operation for expelling the ink or air bubbles is performed, the ink passes between an inner wall of the filter chamber and the air bubbles easily, the air bubbles cannot be expelled sufficiently, and the remaining air bubbles are grown to large sizes immediately. Therefore, there is a problem such that the cleaning operation needs to be performed frequently, and hence ink is consumed uselessly.